Masonry structures are porous and are susceptible to cracking due to distortion caused by movement of their foundation, vibration, and/or drying out subsequent to their construction. In addition, below grade structures are often subjected to hydrostatic pressure from ground water. Therefore, waterproofing and sealing below grade masonry structures have been major concerns for a number of years. Masonry structures have been coated with various tar-based and asphaltic compositions. These compositions are relatively inexpensive and can be applied year-round if heated to a pliable state. However, these compositions generally contain leachable components which can contaminate the surrounding soil. In addition, these compositions contain substantial amounts of organic materials which are attacked by soil- and water-borne microorganisms and have a short useful life before decomposition of substantial pathways through the coatings.
The problem of waterproofing and sealing is even more acute when dealing with sewage systems that contain concrete units such as sewage tanks, clarification tanks and pipes. A coating for sewage systems not only must provide effective waterproofing and sealing but must be able to withstand chemical attack to maintain its effectiveness. Noxious gases, e.g. ozone, methane, hydrogen sulfide and the like, as well as strong acids, e.g. sulfuric acid and the like, microorganisms, caustic and other noxious sewage degradation products can attack a coating and destroy its effectiveness.
The only effective coating used for concrete structural units at present is polyvinyl chloride sheeting. The waterproofing/sealing systems based on polyvinyl sheeting generally have open seams and generally require black mastics or metal fasteners such as nails, etc., to adhere the sheeting to the masonry or concrete surfaces. The sheets are usually UV-sensitive and can be susceptible to fungus and insect attack. In addition, the sheets are difficult to form around non-uniform surfaces, e.g. at the joints, where plastic welding may be required, and the nails puncture the sheet and may puncture cement blocks to provide a direct water channel into the interior of the block wall. In some instances where pre-molded polyvinyl chloride is used, the concrete must be poured around the mold; i.e. the coating is placed only during the building of the structural unit.
Beyond the problems discussed above, the state of the art coating compositions are generally fragile, and they must be protected during backfilling of earth around the masonry structures. Without such protection, the sheets or coatings can be ruptured, torn, pulled down along vertical surfaces by the backfill, etc. Further, many of these coating systems require that the masonry structure be dry or contain only a trace of dampness which requires careful protection of the structure before application of the waterproofing/sealing system.
Therefore, a new, low cost, waterproof and chemically resistant sealant is needed for use in waterproofing applications for concrete sewage units which is durable and has a long effective life span. In addition, a new method of waterproofing and sealing and structures is needed which is useful year round, even in northern latitudes, and which can be applied more conveniently to wet masonry or concrete surfaces.